In most prior adjustable wrenches having a fixed jaw and an adjustable jaw, the adjustable jaw is adjusted and secured in position by a journaled screw which engages corresponding serrations formed on the shank of the adjustable jaw. Such wrenches are often clumsy and difficult to adjust and consume valuable time as the screw is slowly turned to move the jaw.
In addition, once the adjustable jaw has engaged the nut, the jaw often slips or loosens and loses the firm engagement with the nut or bolt as there is nothing to prevent the adjustable jaw from opening except for the user applying finger pressure on the screw to prevent it from rotating. This slippage, common to prior wrenches, inevitably strips the nut or bolt being worked on. Further, such prior tools are also costly to manufacture due to the adjusting screws used in their construction.
A prior adjustable wrench is shown in U.S. Pat. No. 1,397,214 wherein the adjustable jaw is held in varying positions by a retractable clutch. The clutch is disposed in the wrench head and has ratchet teeth formed at its outer end adapted to engage corresponding ratchet teeth formed on the shank of the adjustable jaw. The clutch is spring-biased against the jaw shank and must be retracted to move the adjustable jaw away from the fixed jaw.
The following patents are exemplary of other prior wrenches: U.S. Pat. Nos. 1,004,561; 1,427,918; 1,481,250; 1,511,536; and 1,514,017.